An IOL is an artificial lens implanted in the eye, for example, as a replacement for the natural crystalline lens after cataract surgery or to alter the optical properties of an eye in which the natural lens remains. IOLs include an optic, and preferably at least one flexible fixation member or haptic which extends from the optic and becomes affixed in the eye to secure the lens in position. The optic normally includes an optically clear lens. Implantation of such IOLs into the eye involves making an incision in the eye. It is advantageous, to reduce trauma and speed healing, to have an incision size as small as possible. Some IOLs are foldable so that the IOL can be inserted through a smaller incision into the eye. A variety of instruments have been proposed to aid in inserting such a foldable lens in the eye.
In one method, the surgeon simply uses surgical forceps having opposing blades which are used to grasp the IOL and insert it through the incision into the eye. While this method is still practiced today, more and more surgeons are using more sophisticated IOL inserter devices which offer advantages such as affording the surgeon more control when inserting the IOL into the eye. IOL inserter devices, so called injectors, have recently been developed with reduced diameter nozzles which allow for a much smaller incision to be made in the cornea than is possible using forceps alone. Smaller incision sizes (e. g., less than about 3 mm) are preferred over larger incisions (e. g., about 3.2 to 5+mm) since smaller incisions have been attributed to reduced post-surgical healing time and complications such as induced astigmatism.
The IOL may be made from a variety of materials or combination of materials such as PMMA, silicone, hydrogels and silicone hydrogels, etc.
Two types of IDLs can be distinguished regarding the storage thereof. The hydrophilic IOLs have to be stored in fluid solvent in a container and are loaded to the injector just before inserting them into the eye. In contrast, hydrophobic IDLs can be stored in a cartridge in a dry environment.
In case of hydrophilic IOLs, the IOL must first be loaded into the IOL injector. The loading of the IOL into the injector is therefore a precise and very important step in the process. An example of hydrophilic IOL and injector thereof can be seen in patent specification US2010280521 in which a retainer is provided for holding an IOL in an unstressed state. Before injection, the retainer and IOL are attached to an injector body and a compressor is moved to the closed position to compress the IOL. During injection, the compressor remains on the injector body.
In the patent specification WO2007078602, an apparatus is described for loading a hydrophilic IOL into an injector. The IOL is stored in a vial and is fixed by holder mounts. In course of loading, the vial is pushed to the injector comprising a loading chamber. The loading chamber has a component that when being closed folds the lens. The goal of the apparatus is to prevent the damage of the IOL during loading.
In case of hydrophobic IOLs, the IOL are stored together with the injector and there is no need of loading. Such a construction is described in patent specification EP1481652. Since the IOL is stored in the injector, special provision is needed to prevent a premature injection. Therefore a stop means shall be applied for stopping the movement of the IOL prior to the usage, during shipment and storage. The stop means is frictionally engaged on the lid of the injector, so an accidental removal can release the IOL to be injected.
Unfortunately, providing the injector with additional elements for further decreasing the risk of premature injection would result in a clumsy construction which would disturb the surgeon during injection of the IOL.
As it is seen from the description above, the preparation of hydrophobic IOLs for injection is a complex problem in which the preloaded IOL shall be folded as well as prevent premature injection. Constructions for hydrophilic IOL cannot be used due to the different way of loading and the different characteristic of the hydrophobic lenses. Therefore, there is a need for development of alternative solutions for a preloaded injector that would provide an injection of hydrophobic IOLs in which the folding of the IOL should be carried out in a cartridge prior to the injection but the premature injection is prevented.